US2231686A - Switch structure - Google Patents

Description

Feb. 11, 1941. a 5 W 2,231,686

SWITCH STRUCTURE Filed Aug. 29, 1958 2 Sheets-Sheet l M II Feb. 11, 1941. B. E. SHAW 2,231,686

SWITCH STRUCTURE Filed Aug. 29, 1938 2 Sheets-Sheet 2 (fave/z ioz fizrfozz 2? 6242212 Patented Feb. 11, 1941 PATENT OFFICE SWITCH STRUCTURE Burton E. Shaw, Bristol, Ind., assignor to Penn Electric Switch 00., Goshen, Ind., a corporation of Iowa Application August 29, 1938, Serial No. 227,311

7 Claims.

One object of my present invention is to provide a switch structure in which a plurality of switch units may be operated from a single temperature responsive element and wide range and differential adjustments are possible of being secured by my structure.

Another object is to provide a switch structure which is particularly adaptable for mounting in the bonnet of a furnace so that a temperature responsive element of the switch structure is responsive to the temperature therein and cooperates with a pair of switch units, one for controlling an air circulating fan and the other for controlling the burner system itself, such switch units being commonly called "fan" and limit switches respectively.

Another object is to provide a switch structure which is very sensitive to temperature changes and accurate with respect to operation at exactly the temperatures for which the various range and differential adjustments of the switch have been set.

Still another object is to provide a switch structure in which switch units including permanent magnets to secure snap action are used, the magnets also widening the differential of operation of the switch units to a substantial degree so that cams can be associated with the actuating elements of the switch units in such manner that two cams may be circumierentially adjusted relative to each other to widen or narrow the difierential of operation of the switch units relative to the movement of an actuatin'. device such as a thermostatic member and different range adjustments of the switch units can be secured by movement of the cams to difierent rotated positions relative to the actuating device.

Still another object is to provide a switch 0 structure in which the element of inaccuracy with respect to-the temperature responsive element and the switch unit is reduced to a minimum by the use of cams with rollers coacting therewith, the rollers in turn being operable to 5 actuate the switch units.

A further object is to provide means to eliminate the possibility of one adjustment, when being changed, eflecting change of another of the adjustments of the switch structure.

5 A further objectis to provide a switch structure in which a pair 01 cams may be either adjusted at the factory or adjusted on the job by a very slight change in the assembly of the switch.

u A further object is to provide a switch structure including an additional cam which cooperates with an actuating cam of the switch structure to prevent undesired operation of a switch unit as a result of considerable overrun of the temperature or other condition affecting the 5 switch structure.

Still a further object is to provide a casing for the switch structure which is so split and includes a conduit support so arranged relative to the parts of the casing as to facilitate wiring 0 of the switch units within the casing.

With these and, other objects in view, my invention consists in a construction comprising the arrangement and combination of parts shown by way of illustration in the accompanying draw- 15 ings whereby the objects contemplated are attained, as hereinafter more fully set forth and pointed out in my appended claims. In said drawings:

Figure l is a plan view of a switch structure 20 embodying my invention, portions of the casing being broken away and other portions thereof being shown in section.

Figure 2 is a front elevation of the switch structure showing the front or major portion of 25 the casing removed except for one portion thereof at the lower right hand corner of the figure being shown in section.

Fgure 3 is an enlarged sectional view on the lne 3-3 of Figure 1 showing an adjusting means so for the temperature responsive element of my sw'tch structure.

Figure 4 is an enlarged sectional view on the the 4-4 of Figure 2.

Figures 5 to 13 inclusive are sectional views on 35 the ind cated lines 5 to I3 respectively of Figure 4, Figures 5, '1, 8 and 10 showing only the first element back of the indicated lines, Figures 6 and 9 showing only two elements back of the indicated lines, and Figures 11, 12 and 13 show- 0 ng all the elements back of the indicated lines.

Figure 14 is a sectional view similar to Figure 11 showing a factory fixed adjustment; and

Figure 15 is a sectional view on the line i5l5 of Figure 1.

On the accompanying drawings I have used the reference character C to indicate generally a casing. The casing C has a shallow back portion I0 and a relatively deep front or major portion l2. Extending from the back portion I0 is a conduit support I3 in the form of a flange having a pair of conduit openings I 4. The openings I are adapted to receive the threaded ends of conduits or BX cable fittings from which wires extend into the casing C for electrical connec- I53 tion with terminals l5 of switch units F and L such as fan and limit switches respectively. The major portion |2 may be secured to the back portion H) of the casing C by clips l6 (see Figure 1) entering perforations I! at one side of the casing C and a retainer screw l8 at the other side threaded in a clip l9.

Extending rearwardly from the back portion ll) of the casing C is a tubular support 28. The support 20 is adapted to extend into a bonnet or plenum chamber of a hot air furnace. The support 20 is adapted to contain and support a temperature responsive element such as one of coiled bi-metal indicated as 2| on the drawings. One end of the temperature responsive element 2| is secured to a bracket 22 and the other end is secured to a shaft 23.

The bracket 22 as shown in Figure 3 has an arcuate slot 24 registering with a clamp screw 25. The clamp screw 25 is threaded into an car 26 of a bracket 21'. The bracket 21 is riveted as at 28 to the tubular support 28. The screw 25 may be loosened and the bracket 22 adjusted around the axis of the tube 20 to thereby adjust the anchored end of the bi-metal element 2| so that a dial 29 on the outer end of the rod 23 will read directly in degrees of temperature relative to a pointer mark 30.

Rotation of the rod 23 operates the switch units F and L by reason of an operative connection between the rod and the switch units as will now be described. Each switch unit as shown in Figure 15 includes an arm 3| pivoted on knife edge pivots 32 and cooperating with a leaf spring 33 to separate or engage switch contacts 34 and 35 relative to each other.

A permanent magnet 36 cooperates with an armature 31 of the switch arm 3| to effect snap action of the switch and to widen the differential of the switch to a point where it requires considerable movement of an actuating element or pin 38 to move the switch from closed circuit to open circuit position or vice versa. A spring 39 is interposed between the actuating pin 38 and the switch arm 3| on which there must be tension sufliciently great to overcome the pull of the magnet 36- on the armature 31 when the switch is moved from closed to the open position shown in Figure 13. I

For operating the actuating pin 38, a roller 40 is provided which is carried by an arm 4|. The arm 4| is pivoted on a pin 42 which in turn is supported in the casing C by a bracket 43. The bracket 43 also serves as a support for the fan and limit switch units F and L. A comparatively heavy leaf spring 44 is connected to the arm 4| and bears against the pin 38. This spring is for the purpose of permitting movement of the arm 4| beyond any position to which the pin 38 might be limited without placing undue strain on the roller 48 and cams for operating it which are indicated at 45 and 46.

Thus far I have described the switch unit F. The switch unit L is of identical character and its operating mechanism includes elements 48a, 4| a and 44a similar to the elements 48, 4| and 44. The cams which coact with the roller 40a for actuating the switch unit L are shown at 41 and 48. I also provide an overrun cam 43 for the roller 40a.

Referring to Figure 9, the cam 45 may be considered the on cam for the roller 48 and the cam 46 may be considered the "ofi cam therefor. Dot and dash lines 58 and 5| indicate the respective distances of the periphery of the roller 40 from the center of the shaft 23 when the roller drops to on position during clockwise rotation of the shaft 23 and when it is raised to off position during subsequent counter-clockwise rotation of the shaft 23. As the shaft rotates clockwise due to an increase in temperature, the roller will first drop from the full line position to the dotted line position after passing the lobe 46a of the cam 46 and to the dash line position after passing the lobe 45a of the cam 45. Subsequently when the temperature decreases, the cam lobe 45a will engage the roller to raise it from the dash line to the dottedline position and finally the lobe 46a will engage it to raise it to the full line position. Accordingly it is obvious that the greater the distance between the lobes 45a and 46a, the greater will be the differential of operation of the switch unit F.

I provide a convenient and readily settable means to effect such adjustment consisting of a pair of pointers 52 and 53 which are rotatable on the shaft 23. These pointers coact with the dial 29 to indicate the temperature at which the switch F will be turned off or on respectively. To effect an operative connection between the pointer 52 and the cam 46 I provide an extension 52a on the pointer which passes through a slot 45b of the cam 45 and enters an opening 46b of the cam 46. The slot 45b is arcuate so that the cam 45 can be adjusted rotatably without interference by the extension 52a. A similar operative connection is provided between the pointer 53 and the cam 45 consisting of an extension 53a entering an opening 450 of the cam 45.

The pointers 52 and 53 may be locked relative to the dial 29 by a lock nut 54. The dial itself is non-rotatable on the shaft by reason of having an opening which fits the shaft, the shaft itself having flattened sides 55. The pointers 52 and 53 have circular openings so that they may rotate on the shaft. Between the pointers, a washer 55 is provided having an opening which fits the shaft whereby the washer is siidable but non-rotatable relative to the shaft. In this way the adjustment of one pointer will not be transmitted to the other one when it is desirable to adjust but one of them.

Referring to Figure 11, the cam 41 is the off cam. for the limit switch L, the cam 48 is the on cam therefor and the cam 49 is an overrun cam therefor. In Figures 7 and 8 pointers 51 and 58 are shown for the cams 48 and 41 respectively.

Referring to Figure 9, the pointers 51 and 58 have extensions 51a and 58a. These extend through an arcuate slot 45d of the cam 45 and (see Figure 10) through an arcuate slot 460 of the cam 46. The extension 51a terminates in an opening 41a of the cam 41 while the extension 580 extends on through a slot 41b of the cam 41 and terminates in an opening 480. of the cam 48. Thereby the cam 41 is adJusted by the pointer 58 and the cam 48 is adjusted by the pointer 51.

The cam 48 is provided with an arcuate slot 48b in which the extended end of the extension 58a is located while the overrun cam 49 is provided with an arcuate slot 49a receiving the extended end of the extension 51a. The slots 48b and 49a eliminate the necessity of the extensions 58a and 51a stopping between the faces of the cams 41 and 48 and between the faces of the cams 48 and 48 respectively but permit them to extend well through the cams 46 and 41 as shown by the ex tension 58a in Figure 2.

To prevent the movement of any one of the 75 element.

pointers 52, 53, 51 or II when another one of them is being adjusted, washers Ila and 56b in addition to the washer 56 are provided, Each of these washers is slidable and non-rotatable on the shaft 23. Also the overrun cam 49 is non-rotatable on the shaft 23 and is normally held against a shoulder 23a thereof by the lock nut .54. The overrun cam 49 as shown in Figure 11 is a circumferential extension of the cam 41 so that when the cam 4'! is adjusted clockwise from the position shown in Figure 11 there will still be a raised cam lobe effective to prevent return of the limit switch L to on position when the cam shaft 23 rotates beyond its normal degree of rotation (about 180).

If desired, one of the pointers 51 or 58 can be omitted and the cams 41 and 48 fixed relative to each other by a factory adjustment as shown in Figure 14. This adjustment consists of a screw 59 extending through an arcuate slot 410 of the cam 41 and screwed into a threaded opening 480 of the cam 48. The other pointer is then used merely as a range adjuster. In connection with all of the pointers, it is obvious that the range of the switches F and 'L can be changed since the upper and lower limits are both adjustable so that if both are raised or lowered, the range is thereby changed while if they are spread or moved toward each other, the differential of operation is changed. I have been able to secure a wide range of both range and differential adjustment by the arrangement of cams and pointers disclosed.

Thus far I have described the operation of the switch structure with respect to the switch unit F. The switch unit L operates in a similar manner from the cams 41 and 48. The on and off lobes thereof are indicated at 48d and 41d respectively and correspond to the lobes 45a and 46a. Likewise in operation the roller 40a will turn the switch off when its periphery is elevated by the cam lobe 41d to a distance from thecenter of the shaft 23 indicated by dot and dash line Sla during clockwise rotation of the cams. The lobe 48d when it permits the roller 40a to drop into the indicated line We will turn the switch L on.

In some installations it isdesirable to meet certain ordinances requiring that a switch structure be provided in which the fan switch F cannot be adjusted to a temperature higher than two hundred degrees. This can be accomplished by the use of a screw in the dial 29 which would be sealed in position. Referring to Figures 5 and 6, the screw 60 extends to a position where the pointers I2 and 53 cannot pass it. The pointer 53 has an extension 5317 to engage the screw while the pointer 52 cannot move past the pointer 53 because of being on the opposite side thereof from the screw 60.

Each of the pointers 53, 51 and I4 is provided with an extension to\ keep the hook end of the pointer adjacent the dial 2!. These extensions are shown at 53c, 51b and 58b respectively. On the front of the casing portion l2, a window of Celluloid or the like il may be provided (see Figure 1) through which the dial 2! may be observed. The window 4| overlies the indicia on the dial and the pointer mark I. on the bracket 43.

The various featuresdescribed in connection with my invention all cooperate 'to provide a switch structure which may be readily adjusted to change the range and/or differential of operation thereof. The switch is particularly adapted for operating a plurality of switch units from a single temperature or other condition responsive Some changes may be made in the construction and arrangement of the parts of my device without departing from the real spirit-and purpose of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents, which may be, reasonably included within their scope.

I claim as my invention:

1. In a switch structure, a switch having an actuating element operable to close a circuit at a first position and operable to open a circuit at a second position spaced from said first position, said switch including a. permanent magnet and an armature to give snap action to the switch and to widen the difierential of operation thereof whereby said first and second positions are spaced apart a substantial distance and means for operating said actuating element comprising a pair of simultaneously operable cams, a roller coacting with said pair of cams, temperature responsive means for rotating said cams, one of said cams having a lobe operable to lift said roller beyond said first position as the cams rotate in one direction and the other cam having a lobe operable to drop said roller beyond said second position as the cams rotate in the opposite direction and means for changing the dista'nce between said cam lobes in a direction circumferentially of the rotation thereof whereby to vary the differential of operation of said switch with respect to the travel of said temperature responsive means and for adjusting the position of both of said cams circumferentially of their rotation with respect to said temperature responsive means to vary the range of operation of said switch.

2. In a switch structure, a switch having an actuating element operable to close a circuit at a first position and operable to open a circuit at a second position spaced from said first position,

said switch including a permanent magnet and an armature to give snap action to the switch and to widen the differential of operation thereof whereby said first and second positions are spaced apart a substantial distance and means for operating said actuating element comprising a pair of simultaneously operable cams, a roller coacting with said pair of cams, temperature responsive means for rotating said cams, one of said cams having a lobe operable to lift said roller beyond said first position as the'cams rotate in one direction and the other cam having a lobe operable to drop said roller beyond said second position as the cams rotate in the opposite direction and means for changing the distance between said cam lobes in a direction circumferentially of the rotation thereof whereby to vary the diflerential of operation of said switch with respect to the travel of said temperature responsive means.

3. In a switch structure, a switch having an actuating element operable to close a circuit at a first position and operable to open a circuit at a second position spaced from said first position, said switch including a permanent magnet and an armature to give snap action to the switch and to widen the differential of operation thereof whereby said first and second positions are spaced apart a substantial distance and means for operating said actuating element comprising a pair of simultaneously operable cams, a roller coacting with said pair of cams, condition responsive means for rotating said cams, one of said cams having a lobe operable to lift said roller beyond'said first position and the other cam having a lobe operable to drop said roller beyond said second position, said lobes being spaced apart in a direction circumferentially of the rotation thereof whereby to require a predetermined degree of rotation of said cams between said first and second positions.

4. In a switch structure, a switch having an actuating element operable to close a circuit through the switch at one position and to open a circuit therethrough at a second position, snap acting means to cause the travel of said actuating element from one position to the other to be of substantial extent, temperature responsive means, cams operated thereby for operating said actuating element, one of said cams having a lobe operable to move the actuating element to a position for opening said switch and the other having a lobe operable to move said actuating element to a position for closing said switch, said temperature responsive means including a rotatable shaft, said cams being rotatable thereon, a dial for indicating temperatures, a pair of pointers cooperating therewith and rotatable on said shaft, means for locking said pointers relative to said shaft, one of said cams having an arcuate slot therein, an extension from one of said pointers through said arcuate slot and entering a perforation of the other cam to position it by movement of said pointer relative to said dial and an extension from the other or" said pointers entering a perforation of said first cam to position it by movement of its pointer relative to said dial.

5. In a switch structure, a switch having an actuating element operable to close a circuit through the switch at one position and to open a circuit therethrough at a second position, condition responsive means, cams operated thereby for operating said actuating element, one of said cams having a lobe operable to move the actuating element to a position for opening said switch and the other having a lobe operable to move said actuating element to a position for closing said switch, said condition responsive means ineluding a rotatable shaft, said cams being rotatable thereon, a dial for indicating temperature, a pair of pointers cooperating therewith and ro-. tatable on said shaft, means for locking said pointers relative to said shaft comprising a clamping nut for engaging said pointers with each other and with said dial, one of said cams having an arcuate slot therein, an extension from one of said pointers through said arcuate slot and coacting with the other cam to position it by movement of said pointer relative to said dial, an extension from the other of said pointers coacting with said first cam to position it by movement of its pointer relative to said dial, and 9.

washer on said shaft between said pointers, said washers being slidable and non-rotatable relative to said shaft.

6. In a switch structure, a switch having an actuating element operable to close a circuit at a first position and operable to open a circuit at a second position spaced from said first position,

said switch having an inherently wide differential of operation whereby said first and second positions are spaced apart a substantial distance, and means for operating said actuating element comprising a pair of simultaneously operable cams, each having a lobe top at a substantially uniform distance from its axis of rotation, a control arm coacting with said cams, temperature responsive means for rotating said cams, the lobe top of one of said cams being operable to lift said control arm beyond said first position as the cams rotate in one direction and the lobe top of the other of said cams being operable to retain said control arm between said first and second positions or to drop said control arm beyond said second position as the cams rotate in the opposite direction, and means for changing the distance between said cam lobes in a direction circumierentially of the rotation thereof whereby to vary the differential of operation of said switch with respect to the travel of said temperature responsive means, and for adjusting the position of both of said cams circumferentially of their rotation with respect to said temperature responsive means to vary the range of operation of said switch.

7. In a switch structure, a switch having an actuating element operable to close a circuit at a first position and operable to open a circuit at a second position spaced from said first position, said switch having an inherently wide differential of operation whereby said first and second positions are spaced apart a substantial distance, means for operating said actuating element comprising a shaft, a pair of cams thereon, a control arm coacting with said pair of cams, condition responsive means for rotating said shaft, one of said cams having a lobe operable to lift said control arm beyond said first position and the other cam having a lobe of uniform height to keep said control arm between said first and second positions or operable to drop said control arm beyond said second position, said lobes being spaced apart in a direction circumferentially of the rotation thereof whereby to require a predetermined degree of rotation of said cams between said first and second posi tions.

BURTON E. SHAW.

a fif DISCLAIMER 2,231,686.-Burt0n E. Shaw, Bristol, Ind. SWITCH STRficTURE. Patent dated February 11, 1941. Disclaimer filed June 9, 1942, by the inventor; the assignee,

Penn Electric Switch 00., approving. Hereby enters this disclaimer to claims 1, 2, and 3.

[Oflicial Gazette June 30, 1942.]

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